title: Characterization of the complex between mannose-binding lectin trimer and mannose-binding lectin-associated serine proteases.
abstract: Mannose-binding lectin (MBL) is an oligomeric serum lectin involved in innate immunity. Human MBL is complexed with three types of serine proteases (MASP-1, MASP-2 and MASP-3) and two types of their truncated forms (sMAP and MAp44). When an MBL complex binds to carbohydrates of pathogens, the complement system is activated via the lectin pathway. Human MBL is a mixture of different sized oligomers that range mainly from trimers to hexamers. It has been suggested that different MBL oligomers may have distinct MASP compositions. In the present study, an MBL trimer (MBL-I) exclusive of other oligomers was isolated from human serum by chromatography. Immunoblot analysis of MBL-I revealed that it had been co-purified with MASP-1 and sMAP. This suggests that MASP-1 and sMAP are bound to each other in MBL-I. The MBL-I complex was found to activate C2, but to lack the ability to activate C4 due to the absence of MASP-2.
authors.affiliation: Department of Applied Biochemistry, Tokai University, Hiratsuka, Kanagawa.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Tateishi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kanemoto
authors.forename: Teizo
authors.initials: T
authors.lastname: Fujita
authors.forename: Misao
authors.initials: M
authors.lastname: Matsushita
mesh_terms: D002845:Chromatography; D003167:Complement Activation; D003175:Complement C2 / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D037601:Mannose-Binding Lectin / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D057057:Serine Proteases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D044967:Serum / Q000737:chemistry
chemical_list: D003175:Complement C2; D003181:Complement C4; D037601:Mannose-Binding Lectin; D057057:Serine Proteases